How much current does an Arduino Uno need in his power input ?

Thread Starter

Zouglou LeMagicien

Joined Feb 12, 2019

For a project, i'm using a buck converter to get 5V at the output and connect it to the input of the arduino. To reduce the price of my buck, I need to know how much current does my Arduino Uno need.
I search on internet, but they speak only for the limit current and for the draw, nobody is according to nobody for the value of the current...

Does anyone have a good answer ?



Joined Mar 19, 2019
It depends on what you are powering with the Arduino. But since it is being powered typically from a USB port their max is (500 mA) from a port in USB 2.0; (900 mA) in USB 3.0 although Arduinos rarely use anywhere near max.


Joined Mar 19, 2019
The overhead on the Arduino is only a few mA. But it can supply up to 40mA per output. Rarely does an output use all 40mA. So maybe figure <50mA overhead and <40mA for each output port used. There is no easy answer. I would think 2-300mA @ 5V max would be gracious plenty supply current. And it doesn't have to be 5V. That is the output of the Arduino's voltage regulator and it can be supplied at up to 12V.


Joined Jan 15, 2015
The principe here, is to use the 5V of the buck to power the arduino
And to have the cheapest buck, I want to know how much the Uno needs to run
The reason you can't get a fixed number is because there is no fixed current number. The current draw of the Arduino will depend on what it is doing and what devices it is driving. Just as an example any DIO pin has a max DC current of 40 mA. What's on the pins? What the chip is doing as in how much work determines some of the current draw. There is no fixed number. There is no how much it needs to run number.

EDIT: SamR got it ahead of me. I need to type faster. :)